Collapsible canoes have been available for many years. One early canoe which was well suited for packing is described in U.S. Pat. No. 4,290,157. More recently, a collapsible canoe has been developed and marketed by ScanSport, Inc. An alternative collapsible canoe is described in U.S. Pat. No. 5,615,634.
FIGS. 1 through 4 illustrate a prior art collapsible canoe 10 such as the canoe marketed by ScanSport, Inc. The collapsible canoe 10 has a frame 12 which supports a skin 14. The skin 14 encloses the frame 12 and, when tightly engaged thereover, enhances the rigidity of the frame 12.
FIG. 1 is an isometric view of the collapsible canoe 10 where a portion of the skin 14 has been removed to better illustrate the underlying structure. The frame 12 is has a pair of gunwales 16, to which a series of ribs 18 are clipably attached. A gunwale-engaging clip 20 (shown in FIG. 3) is provided on each end of each of the ribs 18, and is configured to snap onto the gunwale 16. A series of stringer-engaging clips 22 (illustrated in FIG. 4) are fixably attached to each of the ribs 18 to stabilize a series of longitudinal stringers 24, including a central keel rod 26. The stringers 24 and keel rod 26 span the ribs 18 and are cradled by the stringer-engaging clips 22.
The keel rod 26 is symmetrically disposed with respect to the pair of gunwales 16. The keel rod 26 has a bow extension 28, which extends the keel rod 26 to a bow junction region 30 of the pair of gunwales 16, and a stern extension 32 (shown in FIG. 4), which extends the keel rod 26 to a stern junction region 34 of the pair of gunwales 16. Thwarts 36 are provided which are fixably attached to a selected subset of the ribs 18 to stabilize the gunwales 16 and provide additional rigidity to the frame 12. Alternatively, the thwarts 36 could be attached directly to the gunwales 16.
The skin 14 is supported by the frame 12, which the skin 14 spans. A portion of the skin 14 is illustrated in the exploded isometric view of FIG. 2, which shows the region of the skin 14 which covers the bow region of the collapsible canoe 10. The skin 14 has a pair of gunwale sleeves 38, to which are attached a pair of side panels 40. The side panels 40 are in turn attached to a bottom panel 42.
When the collapsible canoe 10 is assembled, the pair of gunwales 16 slidably engage the gunwale sleeves 38. FIG. 3 is a view of section 3--3 of FIG. 1, and better shows the construction of one of the gunwale sleeves 38. Rib openings 44 are provided in the gunwale sleeves 38 to allow attachment of the ribs 18 to the pair of gunwales 16. The gunwale sleeves 38 are constructed of a double-sided polymer-coated woven cloth, having a fabric substrate 46 which is typically woven from a nylon yarn and coated on both sides with a waterproof polymer coating 48, such as vinyl.
The side panels 40 are also constructed of a double-sided polymer-coated woven fabric, coated on both sides with a polymer. The side panels 40 are typically thinner than the gunwale sleeves 38, since the side panels 40 are not subject to the stresses or abrasion to which the gunwale sleeves 38 are subject. Again, the woven fabric is typically woven from a nylon yarn.
The bottom panel 42 of the Scansport collapsible canoe is also formed from a double-sided polymer-coated fabric, coated on both sides with a polymer. The double-sided polymer coated fabric employed for the bottom panel 42 will generally be thicker than that employed in the side panels 40, since the bottom panel 42 is subject to greater stresses and abrasion than are the side panels 40. The woven fabric employed in the bottom panel 42 is again typically woven from a nylon yarn and is generally similar to the material used for the gunwale sleeves 38.
A foam pad 50 is preferably provided, which resides between the bottom panel 42 and the frame 12. While such foam pads 50 have, in the past, typically been simply placed between the bottom panel 42 and the frame 12, in the collapsible canoe 10 the foam pad 50 employed in a ScanSport canoe is bonded to the bottom panel 42, eliminating the chance of water accumulating between the bottom panel 42 and the foam pad 50. Such lamination of the foam pad 50 to the bottom panel 42 is also taught in the '634 patent, which teaches that the foam pad 50 may be alternatively attached to the bottom panel 42 by sewing. The foam pad 50 is typically a closed-cell foam and engages the stringers 24 and the keel rod 26 when the collapsible canoe 10 is assembled. The foam pad 50 mitigates abrasion of the bottom panel 42 when the bottom panel 42 encounters a foreign object such as a rock by providing cushioning between the bottom panel 42 and the frame 12. The foam pad 50 also provides additional flotation capacity in the event that the collapsible canoe 10 is swamped.
The gunwale sleeves 38, the side panels 40, and the bottom panel 42, when sewn together, form the skin 14. A heat sealable tape 52 (shown in FIGS. 2 and 4) is placed over the sewn seams between the bottom panel 42 and the side panels 40, as well as over seams at the bow and stern, where the side panels 40 join each other and are joined to bottom panel extensions 54. The heat sealable tape 52 bonds to both the side panels 40 and the bottom panel 42 to assure that the seams remain water-tight. The seams between the gunwale sleeves 38 and the side panels 40 are not covered with heat sealable tape 52, since these seams are not submerged in normal usage.
As shown in FIG. 4, the skin 14 will preferably include a pair of inflatable flotation compartments 56 which reside between the side panels 40 and the frame 12 when the collapsible canoe 10 is assembled. The inflatable flotation compartments 56, when inflated, help maintain the skin 14 tautly in place on the frame 12. The inflatable flotation compartments 56 also provide increased stability and floatability of the collapsible canoe 10 if swamped. It is preferred for the inflatable flotation compartments 56 to be attached to the skin 14 with straps 58 which pass through strap eyelets 60 in the gunwale sleeves 38 and through the rib openings 44. The attachment of the inflatable flotation compartments 56 with straps 58 facilitates replacement if damaged. Preferably, a flotation compartment support rod 62 is provided on either side of the collapsible canoe 10, and resides between the inflatable flotation compartments 56 and the ribs 18. The flotation compartment support rods 62 provide longitudinal support for the inflatable flotation compartments 56 to improve the appearance of the collapsible canoe 10.
The '634 patent teaches an alternative to the inflatable flotation compartments 56. In the collapsible canoe of the '634 patent, the skin is provided with anti-flex covers which are bonded to the skin on either side so as to form an envelope. A multi-chambered anti-flex air bladder resides in each of the envelopes formed by the anti-flex covers, and the anti-flex air bladders are inflated to both tension the skin and to provide greater rigidity to the collapsible canoe. The anti-flex system of the '634 patent requires the anti-flex covers to be bonded to the skin to form an envelope which anchors the anti-flex air bladders to the skin, increasing the complexity of fabrication of the skin, making replacement difficult, and increasing the difficulty of conforming the shape of the anti-flex air bladders to the shape of the frame. The multi-chamber anti-flex air bladders do not allow for replacement of an individual air chamber which is damaged. Rather, the entire air-bladder must be replaced. Additionally, the anti-flexing system of the '634 patent requires side stringers to retain the position of the anti-flex air bladders, rather than employing free-floating support rods such as the flotation compartment support rods 62 which are employed to provide longitudinal support for the inflatable flotation compartments 56. The side stringers are clipably attached to the ribs and tied in to the bow and stern extensions of the keel rod, complicating fabrication of the frame as well as assembly and disassembly of the collapsible canoe of the '634 patent.
The collapsible canoe 10 preferably also includes end covers 64, which can be attached to the bow and stern of the collapsible canoe 10 with snaps. The end covers 64 provide greater protection against the ingress of water and to improve the appearance of the collapsible canoe 10.
Collapsible canoes such as described above are difficult to assemble and disassemble, since the gunwales 16 tend to bind due to friction between the gunwales 16 and the polymer coating 48 of the gunwale sleeves 38. This binding makes it difficult to insert the gunwales 16 into or remove them from the gunwale sleeves 38. Frequently, lubricants are used to aid in the installation of the gunwales 16 into the gunwale sleeves 38.
Since the gunwales 1.6 are usually constructed from a series of tubular members fitted together, which are liable to pull apart under tension, the gunwales 16 are typically removed by pushing them out of the gunwale sleeves 38 with a tubular member (not shown) of similar diameter to the gunwales 16. This method of removal requires each gunwale sleeve 38 to have a passage 66 which is sized only slightly larger than the gunwales 16, to provide guidance for the tubular member to prevent it from sliding alongside the gunwale 16 and wedging it into the gunwale sleeve 38. The problem of binding is aggravated by having gunwale sleeves 38 with passages 66 only slightly larger than the gunwales 16, as illustrated in FIG. 3.
The use of the double-sided polymer-coated fabric for the bottom panel 42 makes it difficult to reliably bond the foam pad 50 thereto. When the polymer coating is a vinyl, such coatings typically include plasticizers, which generate volatiles which interfere with the bonding of the foam pad 50 and can result in delamination of the foam pad 50 from the bottom panel 42. While the foam pad 50 could be sewn to the bottom panel 42, as is taught in the '634 patent, such attachment complicates fabrication of the skin 14. Additionally, when the foam pad 50 is sewn to the bottom panel 42, leaks in the bottom panel 42 or the foam pad 50 could allow water to accumulate between the bottom panel 42 and the foam pad 50.
The prior art devices for inflatably tensioning the skin with respect to the frame do not allow for replacement of individual elements which may be damaged, and do not provide an option between temporary or permanent attachment to the skin.
Thus, there is a need for an improved skin for a collapsible canoe which will assure the easy assembly and provide a skin which is easier to manufacture without risk of delamination. There is also a need for a skin which uses individually replaceable elements to tension the skin and which provides flexibility in the manner of attachment of such elements to the skin.